1. Field of Disclosure
This application relates to equipment diagnostics and, in one embodiment, technology that facilitates diagnoses of malfunctioning automotive alignment systems.
2. General Background and State of the Art
Automotive diagnostic and repair equipment sometimes fails to function during use or, because of improper use, fails to successfully accomplish its desired function. In particular, equipment used for automotive wheel alignment may be susceptible to malfunctions during use that may be difficult to detect or correct at a later time. This is due to the sensitivity of such equipment to environmental disturbances, as well as to the large number of cooperative components involved in wheel alignment systems.
One example of this problem is during wheel alignment. Wheel alignment is a process of adjusting the angles of wheels on a vehicle so that they are generally perpendicular to the ground and parallel to one another. The purpose of these adjustments is to attain maximum tire life, as well as to keep the vehicle tracks straight when driving along a straight and level road. In order to adjust the wheel angles to achieve proper wheel alignment, the actual wheel angles must first be measured. Then, the requisite adjustments may then be calculated. Two particular angles that are often utilized in wheel alignment methods are commonly referred to as “camber” and “toe.” Camber, which is typically measured in degrees, is the angle of the wheel's deviation from a vertical plane. Therefore, camber is angle of the wheel that is seen when viewed from the front of the vehicle. If the top of the wheel is leaning away from the center of the car, the camber is positive; if it is leaning in toward to center of the car, then the camber is negative.
Toe is the difference in distance between the front of two tires and the back of those tires. It is normally measured in fractions of an inch, and is usually set close to zero, meaning that the wheels are substantially parallel to one another. “Toe-in” means that the fronts of the tires are closer to each other than the rears; “toe-out” is the opposite situation. These, as well as other wheel alignment parameters, are quantified through sensitive measurement techniques that can encounter significant errors in the event of an equipment malfunction or environmental disturbance. Some types of systems for measuring such wheel alignment parameters may be more sensitive than others, though almost all are susceptible to such malfunctions and disturbances.
Wheel alignment may involve placing instrumentation on each of a vehicle's four wheels. The instrumentation may include a set of optical targets clamped to each wheel. An optical sensor means such as a camera is situated to view the targets, and a light may be directed toward the targets with sufficient intensity to cause the targets' reflections to be detected by the optical sensor means. The optical sensor means may view a target located on each wheel and forms an image of each target. Electrical signals corresponding to each of the images may be transferred to a processor, which correlates the perspective image of each of the targets with the true shape of each target. The processor may then relate the known geometric dimensions of the target with the dimensions of corresponding elements in the perspective images, and can thereby calculate the alignment of the wheels. Such methods are well known in the art, and described in detail in U.S. Pat. Nos. 5,535,522 and 5,809,658, for example, each of which is incorporated herein by reference.
Unfortunately, such procedures and systems can encounter a variety of operational problems due to the sensitivity of the various system components and the sheer number of components that must cooperate during operation of the system. Unfortunately, in the case of malfunctions during use of such equipment, the operator often lacks the skills necessary for diagnosing the malfunction or correcting it. Technicians who service the equipment, on the other hand, might have the ability to diagnose and correct such problems, but are often unable to successfully trouble-shoot operational problems because they are unable to be present during the malfunction. By the time a service technician arrives on the premises, the problem may no longer be observable. This sometimes leads to the problem not being solved and, in some instances, to the costly replacement of components erroneously thought to have been malfunctioning.
Therefore, what is needed is an operational malfunction diagnostic method that allows for a skilled technician to diagnose an operational problem even after the problem has occurred and is no longer apparent.